I have done the calculations for power requirements that I would need arround 1000w of power to be able to keep a constant speed of 20mph on a 5 degree slope with a 70kg rider and 5 mph wind speed. I have done all the friction, gravity and air resistance calculations and ended up at arround 950w power requirements. Other forces can be neglected.

I am not sure what would be the next step. How do I pick the most suitable 1kw motor and calculate required amount of rpm and torque to produce 20mph?